cleaning and disinfecting of underground and overhead water tanks at both the campuses of csir igib , mechanized cleaning of underground & rcc/pvc/ oh tank with six stages process mentioned as under:- mechanical dewatering . desiliting and removal of left over dirty water and sludge with sludge removal pump . cleaning of walls , ceiling and floor by high pressure water jet with the help of equipment which create a pressure of 100 to 150 bar with antibacterial agent license from food and drugs administration ( fda ) and certificate by a govt . approved laboratory for non-toxicity of antibactrial for tank cleaning as per oecd guidlines for disinfecting the tank from all harmful bacteria , fungi , algae & protozoan . the active ingredient shall be benzalkonium chloride solution ip 4% w/v/equivalent similar compound as per the direction & approved by engineer-in-charge . removal of remaining sludge from the floor with help of industrial vacuum cleaner . spraying of non-toxic , bio degradable eco friendly anti - bacterial agent for tank cleaning certificate by govt . approved laboratory as per the oced guidelines 423 adopted on 17th december 2001 for disinfect the tank from all the harmful pathogens . treatment of inside the tank by exposing u . v radiation to kill further suspended of floating bacteria if any . pvc/rcc o/h tanks ( litres )